CRP tests may need to be repeated to diagnose non-radiographic axial spondyloarthritis

C-reactive protein levels in non-radiographic axial spondyloarthritis patients are likely to change within weeks of initial testing and should therefore be tested again before denying a patient of anti-tumor necrosis treatment, according to a study published in BioMed Central.

2. At week zero, patients were randomized to receive the placebo, certolizumab pegol 400 mg every four weeks or certolizumab pegol 200 mg every other week. One subjects who failed screening due to the CRP level was permitted to a retest.

3. CRP level was assessed at screening, baseline and at nine other times leading up to the 24-week mark. At each assessment, serum samples from each participant were collected.

4. Sixty percent of samples were analyzed in the European central laboratory with a lower limit of quantification CRP assay at 3 mg/L. North and Latin America accounted for 40 percent of the samples, which were analyzed with a high sensitivity assay at 0.1 mg/L.

5. Of the 325 study participants, 107 were given the placebo treatment and 218 were given certolizumab pegol. Baseline CRP assessment results for 106 placebo patients were as follows:

Researchers concluded non-radiographic axial spondyloarthritis patients who have normal CRP levels and no signs of inflammation on MRI and should have the CRP test repeated after at least four weeks. Subsequent testing shows there is a high chance of finding elevated CRP levels after initial testing, which would make the patient eligible for anti-TNF treatments.